High-yield purification process of singlewalled carbon nanotubes

Reproducible high-yield purification process of singlewalled carbon nanotub es was developed by combining two-step processes of thermal annealing in ai r and acid treatment. The process involves the thermal annealing in air wit h the powders rotated at temperatures of 470 degreesC for 50 min, which bum s out the carbonaceous particles, and an acid treatment with HCl for 24 h, which etches away the catalytic metals. Control of the annealing temperatur e and rotation of the sample are crucial for high yield. Our reproducible o ptimal purification process provides a total yield of about 25 similar to 3 0 wt % with less than 1 wt % of transition metals, which was confirmed by t he thermogravimetric analysis. Bundling and length control depending on the different acid treatments will be further discussed.